Her fatalistic mind-set and her family's ensuing heartbreak unfolded for all the world to see on her wide-open Facebook page.

About an hour before police believe she jumped in front of a city bus on Hylan Boulevard Dec. 27, the 15-year-old New Dorp High School sophomore wrote the following unedited message on her Facebook page: "... Nd ill die tomight crying over you.."

That sparked a series of panicked responses from her mother and another relative, before her family discovered what had happened to her and that she'd been taken to Staten Island University Hospital, Ocean Breeze, in critical condition. She died on Monday.

Police said she was carrying a suicide note when the bus hit her. An autopsy determined the cause of death to be suicide; there were blunt-impact injuries to her head, including skull fractures, the city medical examiner's office said earlier tonight.

Amanda's uncle, Keith Cummings, said she had been tormented by bullies from her days in middle school, and that things had gotten particularly bad after she had begun seeing an older teen romantically. That sparked jealousy on the part of another high school girl, and a series of nasty text messages and threats from a group of girls, he said.

Still, the bullying predated high school, Keith Cummings noted. "She was bullied in middle school, too. She would come home with no jacket."

The suicide note, Cummings said, made reference to her romantic troubles and a recent breakup with the older teen.

After she was struck by the bus, Cummings said, a couple of Facebook posts mocked her and what happened to her, but those posts have since been deleted, he said.

Her Facebook status updates paint a picture of a young girl crying out for help. The following is verbatim:

"I want to die," she wrote on Oct. 20.

"R.I.P. Amanda Cummings, she passed away from a heartattack 30minutes ago, If u read this & wuldnt care stop reading, If ud go to my funeral (LMS),If ud cry or be sad comment with a heart. make this ur status nd see what u get," she wrote Nov. 16.

"ill just go (expletive) myself, just like u said baby, then ill go kill myself, with these pills, this knife, this life has already done half the job. -___-," she wrote on Dec. 1.

On Dec. 3, after what she referred to as the "worst sat night evr," she wrote, "Mad people are turning against me :'( im spending this sat nitealone in my room crying."

And at 4:58 p.m. Dec. 27, the day she was struck by the bus, she wrote, "So much pain right now. Everyones ignoring mee. Fml." That last is a commonly used texting acronym for the phrase, "[expletive] my life."

This afternoon, Miss Cummings' classmates at New Dorp High School recalled some of the bullying she faced, both in person and online.

"That's everywhere," said junior Brianna Council, 16, of South Beach. "A lot of people are afraid to say how they feel, but on Facebook, all of a sudden, people have guts."

Miss Cummings was taunted because of her "unique" style and brightly colored makeup, Miss Council and Miss DeLorenzo recalled.

"Her casual was heels and a skirt. Other people made fun of her for that," Miss DeLorenzo said.

And while families often find solace in online messages of support after a tragedy, for Miss Cummings' relatives, those postings had the opposite effect, as dozens and dozens of teens prematurely wrote "rest in peace" comments days before her death.

Her sister, Dawn Weber, responded angrily on Dec. 28, a day after she was struck: "If my sister lives, you all need to stay out of her life. Every one of you 'so called' friends need to GO AWAY. You will never see her again. I wish she never went to that public toilet of a high school and met any of you drug addicted horn dogs, who get little girls drunk & high, then take advantage of them."

Miss Cummings' death caught the attention of state Sen. Jeffrey D. Klein (D-Bronx), who looks to introduce a state law to make cyber-bullying into a criminal offense under the state's stalking, aggravated-harassment and criminal-impersonation statutes. The law is expected to have an early co-sponsor in state Sen. Diane Savino (D-North Shore/Brooklyn).

The rise of social networks, cell phones and the Internet means that children and teens can't escape their bullies by simply avoiding them at school or going home, he said.

"It's far worse, because it continues even after school has ended," Klein said.

George Anthony, co-founder of the "Stand Up & Lead" initiative to train students to be peer leaders in dealing with bullying -- which is coming this weekend to Markham Intermediate School -- said he and co-founder Lindy P. Crescitelli would be willing to offer support or training at New Dorp High School, or to the family of Miss Cummings.

"You can't help but be affected by it, to see this beautiful girl," Anthony said. "Just looking at her was like a light, and she must have been a light to her family. I know as a parent, that light is missing in their life now."

He said sometimes it can take just one student trained in how to respond to bullying, in what to do or say to a bullying victim, to protect that person from a bully or from herself.

Miss Cummings' death also drew the notice of "Panic! At The Disco" frontman Brendon Urie, who sent a heartfelt note to a Staten Islander who notified him of the death via Facebook, and told him Miss Cummings was a fan of his music.

Urie posted a video of a hit single of the band's on his Facebook page and wrote, "For Amanda."